The invention relates to an energy storage module for a device for supplying voltage, in particular, of a motor vehicle, comprising a plurality of prismatic storage cells which, stacked in at least one row, are arranged behind one another and are braced between two end plates by way of tie rods.
In a device for supplying voltage to a motor vehicle usually called a battery, a plurality of energy storage modules is mostly used for the drive of the vehicle, for example, of electric vehicles or hybrid vehicles. A respective energy storage module typically consists of a plurality of stacked prismatic storage cells. The individual storage cells contain electrochemical cells of the battery. The stack of individual storage cells is usually braced by means of a mechanical end plate and tie rods to form the energy storage module. In addition to mechanically fixing the modules with respect to one another, the end plates and tie rods especially have the purpose of counteracting a deformation as a result of gas pressure changes which occur during the operation in the electrochemical cells arranged in the interior of the modules. As a rule, such energy storage modules require a cooling in order to ensure the operating temperature.
It is an object of the present invention to indicate an energy storage module for a device for supplying voltage, which can be produced in a simple manner and from which the cell heat can be effectively removed.
The object is achieved by means of the combinations of characteristics of the independent claim. The dependent claims indicate advantageous embodiments of the invention.
The object is therefore achieved by an energy storage module for a device for supplying voltage, particularly of a motor vehicle, comprising a plurality of prismatic storage cells. The storage cells are stacked in at least one row and arranged behind one another and braced between two end plates (also called pressure plates) by means of at least one tie rod. The at least one tie rod is simultaneously constructed as a heat-conducting plate for removing the heat from the storage cells to a cooling device.
The tie rod or tie rods carry out several functions simultaneously. The tie rods fix the storage cells during the mounting and subsequently brace the end plates. Furthermore, at least one tie rod is simultaneously constructed as a heat-conducting plate. The tie rods can therefore also be called tension elements or fastening elements.
Because of the geometrically narrow dimensions of the cells, the cell heat can no longer be sufficiently removed by way of the cell floor in conventional modules. According to the invention, the tie rod is additionally used as a heat-conducting plate or a heat-conducting plate arranged under the module is simultaneously used as a tie rod. This results in a one-piece further development, according to the invention, of the tie rod and the heat-conducting plate. The heat-conducting plate, which under certain circumstances may already exist for the cooling, is thereby pulled up laterally. Separate lateral tie rods will therefore not be necessary. The tie rods according to the invention, constructed as heat-conducting plates, now have several functions: On the one hand, they are used for cooling the cell module and, on the other hand, for bracing the storage cells. In addition, the laterally pulled-up heat-conducting plate or the tie rod constructed as a heat-conducting plate has the advantage that the storage cell cannot laterally slip during the mounting.
In a particularly preferred development, it is provided that the storage cells have connection terminals which, in the case of all storage cells, are jointly arranged on a front side of the energy storage module. In this case, a first part of the tie rod rests at least partially against the back side of the energy storage module. The back side is defined as the side situated opposite the front side. A second part of the same tie rod rests at least partially against one of the two lateral surfaces of the energy storage module. The “lateral surfaces” extend between the two end plates as well as between the front side and the back side. “Resting” of the tie rods on the energy storage module applies particularly to a resting with a thermally conductive contact. In particular, the tie rods developed as heat-conducting plates are glued to the back side and/or the lateral surfaces and/or a heat-conducting paste is used.
Furthermore, it is advantageously provided that the second part of the tie rod is connected with the laterally two end plates. The bracing and the force transmission therefore take place of the energy storage module. Furthermore, it is an advantage that the first part of the tie rod is spaced away from the end plates. In particular, no connection is provided here between the first part of the tie rod and the end plates. The distance measurements between the end plates and the first parts of the tie rod should be selected corresponding to the required air and creep gaps.
Furthermore, it is preferably provided that the second part of the tie rod extends over the entire height of the energy storage module. The height is defined from the back side to the front side of the energy storage module. As a result, the tie rod utilizes the complete lateral surface of the energy storage module for the heat transmission.
In particular, several tie rods are provided. Two tie rods, with lateral contacts and developed as heat-conducting plates, are particularly preferred.
Still further tie rods, which are not constructed as heat-conducting plates, may be provided between the rows of storage cells.
In the variant with at least two tie rods, it is particularly preferably provided that a first part of a first tie rod and of a second tie rod, each developed as heat-conducting plates, rest at least partially against the back side of the energy storage module, a second part of the first tie rod and of the second tie rod each resting at least partially against one of the two lateral surfaces of the energy storage module.
As an alternative, a first tie rod is arranged on the front side (between the connection terminals) and a second tie rod is arranged on the back side. The two tie rods are then connected on the front side or back side with the end plates. Particularly the lower tie rod (on the back side) replaces the conventional heat-conducting plate. In this alternative, the bracing and the force transmission does not take place laterally of the energy storage module but on the front and back side.
It is further an advantage that a single tie rod consists of a single metal plate. The respective tie rods can therefore be produced in one piece.
In order to ensure a sufficient heat transmission, the following proportions are preferably provided: At least 10%, particularly at least 50%, particularly at least 75% of the surface of the back side of the energy storage module is in heat-conducting contact with the tie rod or the tie rods. Furthermore, at least 10%, particularly at least 50%, particularly at least 75% of the surface of at least one of the two lateral surfaces of the energy storage module is in a heat-conducting contact with the tie rod resting against them.
The end plates (also pressure plates) preferably have a thermally insulated construction with respect to the storage cells.
The providing of at least two tie rods constructed as heat-conducting plates has the advantage that the energy storage module can be mounted in an easy fashion. In this case, the tie rod is preferably glued to the storage cells. Furthermore, an electric insulation layer is arranged between the storage cells and the tie rods. By means of the two-part construction, on the one hand, the insulation layer is not damaged during the joining and, on the other hand, the adhesive remains evenly distributed.
In the following, the invention will be explained in detail by means of the drawing.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.